JP2019528558A - Infrared emitter - Google Patents

Abstract

The invention comprises an infrared emitter having a cladding tube made of quartz glass surrounding a heating filament as an element emitting infrared radiation, the element being connected to an electrical connector outside the cladding tube via a current feedthrough About. In order to improve the service life and power density, according to the invention, the heating filament comprises a carrier plate having a surface made of an electrically insulating material, whereby the surface generates heat when a current flows It is proposed to be covered with a printed conductor made of the material to be used.

Description

  The present invention comprises an infrared emitter having a cladding tube made of quartz glass surrounding a heating filament as an element emitting infrared radiation, the element being connected to an electrical connector outside the cladding tube via a current feedthrough About.

  Infrared emitters according to the present invention exhibit two-dimensional or three-dimensional radiation characteristics. They are used for example for polymerizing plastic materials or for curing lacquers or for drying paints on heated articles, but also for heat treatment of semiconductor wafers in the semiconductor industry or in the photovoltaic industry.

An infrared emitter known in the prior art has a coiled resistance wire or resistance tape as a heating conductor or heating filament inside a glass cladding tube. The wire or tape has no or essentially no contact with the cladding tube. Heat transfer from the resistance wire to the cladding tube is essentially performed by thermal radiation. Heating conductors, also called heating filaments, are used as incandescent lamps, infrared emitters or conductive incandescent filaments in glow furnaces, glow wires or glow coils, generally flat or twisted or coiled tape around its longitudinal axis Exists in an elongated form. Carbon fiber based heating filaments exhibit good mechanical stability with relatively high electrical resistance, and they tolerate relatively rapid temperature changes.

  In the case of such an infrared emitter, an electrical resistance element made of a resistive material is an element that emits the actual infrared radiation of the emitter. Since the quartz glass cladding tube is essentially transparent to infrared radiation, the radiation emitted by the resistive element is transmitted to the heated article without significant radiation loss.

  With regard to the electrical properties, a particular focus is on the electrical resistance of the heating filament. The electrical resistance should on the one hand be constant over time even during exposure to the load, so that on the other hand it can also be operated with a short length of heated filament at a common voltage (eg 230 V). Must be as high as possible.

  In the case of a tape-like heating filament, the nominal electrical resistance can in principle be adjusted by the cross section, in particular by the thickness of the tape. However, the thickness of the tape can only be reduced to a limited extent given the mechanical strength and a given minimum service life. This limitation is particularly noticeable when the heating filament in use is exposed to high mechanical loads, such as in the case of long irradiation lengths of, for example, 1 m or more.

  An infrared emitter with a tape-like carbon heating filament is known, for example, from DE 100 0 437 A1 (DE 100 29 437 A1). The coiled carbon tape is disposed at a distance from the wall of the cladding tube made of quartz glass, and is disposed along the central axis. A contact portion with the connection lug is provided at the end of the carbon tape, and this is guided to the external electrical connector through the crimping region of the cladding tube. The inside of the cladding tube is evacuated during installation to prevent changes in the resistance of the heating element due to oxidation. The output density of the carbon emitter is relatively high because the surface area of the coiled carbon tape is larger than that of the infrared emitter having the metal heating element. They are therefore also suitable in principle for applications where the emitter length is limited to less than 1 meter. However, the problem is that the coiled tape does not make the radiation properties completely uniform, but has areas with higher power density (so-called hot spots) and lower power density (cold spots). This has to be taken into account during its use, in particular in the case of panel radiators (Flaechenstrahler) by making the radiation more uniform by keeping the distance from the radiating article greater. However, this means sacrifices the efficiency of the emitter.

  In addition to infrared emitters with carbon heating filaments, emitters with so-called Kanthal (R) heating elements are also known. They exhibit a broadband infrared spectrum and typically operate at temperatures up to 1000 ° C. The disadvantages with respect to radiation properties lacking uniformity are similar to those described above for emitters with carbon heating filaments.

An infrared heater with a Kanthal coil is known, for example, from US Pat. No. 3,699,309 (US Pat. No. 3,699,309). The Kanthal coil is placed in a glass cladding and is supported on a cylindrical rod having a semicircular cross section made of ceramic fiber material (Al ₂ O ₃ —SiO ₂ ). This support is intended to prevent Kanthal coil "hot spots". This is disadvantageous in that the radiation range of the infrared emitter is no longer in the radial direction 360 ° according to the circumference of the cladding, but rather is reduced only by the area of the support rod in contact with the Kanthal coil.

Technical Problem Therefore, the object of the present invention is to have a high radiation output per unit area, especially high enough sheet resistance to be able to operate at a general industrial voltage of 230 V even with a short irradiation length of 1 m or less. It is to devise an infrared emitter characterized by having a (spezifische Flaechenwiderstand) and having a long service life.

SUMMARY OF THE INVENTION The above-mentioned problem is based on an infrared emitter of the type mentioned at the outset, and according to the invention, the heating filament comprises a carrier plate having a surface made of an electrically insulating material, so that the surface can flow current. This is solved by being covered with a printed conductor made of a material that generates heat when heated.

  The invention is based on the principle of devising an infrared emitter in a quartz glass cladding, in which case a carrier plate having a surface made of an electrically insulating material forms a heating filament. In this connection, the carrier plate itself is made of an electrically insulating material so that its entire surface is electrically insulating. The carrier plate is excited to emit radiation in the infrared spectral region by a printed conductor applied to at least one surface of the carrier plate that generates heat when a current flows. The optical and thermal properties of the carrier plate provide absorption in the infrared spectral region, which is the wavelength range of 780 nm to 1 mm. Thus, the portion of the carrier plate heated by the printed conductor is the element that emits the actual infrared radiation.

  Alternatively, only a partial region of the surface can be made electrically insulating, for example by an electrically insulating material applied to the carrier plate in the form of a surface layer. In this case, the printed conductor covers only the electrically insulating region of the surface or surface layer. In this way, the radiation characteristics of the carrier plate as an element that emits infrared radiation can be locally optimized.

  Since the printed conductor connected to the carrier plate is in direct contact with its surface, a particularly small infrared emitter is obtained. Due to the compact design of the element that emits infrared radiation, it is possible to perform local irradiation focused on a small surface with high radiation density.

  In contrast to infrared emitters according to the prior art, in which the resistive element made of resistive material is the actual heating filament of the emitter, the resistive element of the infrared emitter according to the invention is here in the form of a printed conductor, It is used to heat other components referred to herein as “substrates” or “carrier plates”. Heat transport from the printed conductor to the carrier plate is mainly performed by heat conduction. However, it can also be based on convection and / or thermal radiation.

  Because it is incorporated in a cladding tube, the infrared emitter according to the invention is protected during use from ambient influences such as, for example, an oxidizing atmosphere. This results in a high radiation output with relatively uniform radiation characteristics that are essentially independent of ambient influences. In addition, embodiments having a cladding tube also facilitate installation and possibly maintenance of the emitter.

  A preferred embodiment of the infrared emitter according to the invention consists of the material of the printed conductor covering the carrier plate being a non-noble metal.

  Non-noble metal printed conductor materials are characterized by high specific resistance over a small surface area, which results in high temperatures even at relatively low current flows. Unlike printed conductors with a high proportion of noble metals such as platinum, gold or silver, printed conductor materials made of non-noble metals are very inexpensive without compromising their electrical properties.

  The carrier plate, on which the heating conductor is mounted, is incorporated in a quartz glass cladding tube, thereby preventing corrosion attack of the printed conductor, whether chemically and / or mechanically, by local ambient conditions. As a result, the service life of the printed conductor is extended. Print conductors made of non-noble metals or non-noble metal alloys are particularly sensitive to this corrosion attack.

Advantageously, the printed conductor material is tungsten (W), molybdenum (Mo), silicon carbide (SiC), molybdenum disilicide (MoSi ₂ ), chromium silicide (Cr ₃ Si), polysilicon (Si), One or more components from the group of aluminum (Al), tantalum (Ta), copper (Cu) and heat resistant steel are included. Such printed conductor materials have an ohm per square (also referred to as specific sheet resistance) in the range of 50 to about 100 ohms / square. Due to their respective electrical and thermal properties, this group of materials performs their function of thermal excitation of the carrier plate of the infrared emitter according to the invention and can be manufactured more inexpensively.

  Furthermore, it has been found advantageous when the carrier plate is formed by at least two layers of material. In this connection, the carrier plate may be formed by a base material layer and a surface material layer, so that the two material layers may differ in their electrical resistance or if the electrical resistance is equal. May contain different irradiance (Strahlungsemissivitaet). This makes it possible to optimize the optical and thermal properties of the carrier plate as an element that emits infrared radiation and thus its radiation properties for individual applications. Of course, this advantageous embodiment is not limited to two-layer systems stacked on top of each other. The material layers may likewise be arranged in close proximity or adjacent to each other.

  With regard to the material of the carrier plate, it has been found advantageous if it comprises a composite material formed by a matrix component and an additional component in the form of a semiconductor material.

  The material of the carrier plate is thermally excitable and includes a composite material formed by a matrix component and a semiconductor material as an additional component. The optical and thermal properties of the carrier plate provide absorption in the infrared spectral region. Considered as a matrix component are oxide or nitride materials in which a semiconductor material is embedded as an additional component.

In this connection, it is advantageous if the matrix component is quartz glass, preferably having a chemical purity of at least 99.99% SiO ₂ and a cristobalite content of at most 1%.

  Quartz glass has the aforementioned advantages of good corrosion resistance, temperature resistance and temperature change resistance, and is available in high purity. It is therefore a substrate material or carrier plate material that is considered even in high temperature heating processes with temperatures up to 1100 ° C. No cooling is necessary.

  If the cristobalite content of the matrix is low, i.e. 1% or less, the tendency to devitrification is low, which in turn guarantees a low risk of crack formation during use. As a result, the stringent requirements regarding particle deficiency, purity, and inertness often evident in semiconductor manufacturing processes are also met.

  The heat absorption of the carrier plate material depends on the proportion of additional components. Therefore, it is desirable that the weight fraction of the additional components is advantageously at least 0.1%. On the other hand, a high volume fraction of additional components can adversely affect the chemical and mechanical properties of the matrix. Considering these points, the weight fraction of the additional component is preferably in the range of 0.1% to 5%.

  In a preferred embodiment of the infrared emitter, the additional component comprises a semiconductor material in elemental form, advantageously elemental silicon.

  The semiconductor includes a valence band and a conduction band, which may be separated from each other by a forbidden band with a width up to ΔE≈3 eV. The conductivity of a semiconductor depends on how many electrons can jump over the forbidden band and reach the conduction band from the valence band. Basically, semiconductors generally have low conductivity at room temperature, since very few electrons can jump over the forbidden band at room temperature and reach the conduction band. However, the magnitude of semiconductor conductivity essentially depends on its temperature. As the temperature of the semiconductor material increases, so does the probability that there is sufficient energy to lift the electrons from the valence band to the conduction band. Therefore, the conductivity of the semiconductor increases with increasing temperature. Thus, when the temperature is sufficiently high, the semiconductor material exhibits good conductivity.

  The fine regions of the semiconductor phase in the matrix, on the one hand, act as optical defects, making the carrier plate material look visually black or gray-blackish at room temperature, depending on the thickness. On the other hand, this defect also affects the overall heat absorption of the carrier plate material. This is essentially due to the characteristics of the finely distributed phase of the semiconductor that exists in elemental form, and accordingly, the energy between the valence and conduction bands (bandgap energy) decreases with temperature. On the other hand, if the activation energy is high enough, the electrons are lifted from the valence band to the conduction band, which is accompanied by a clear increase in the absorption coefficient. The thermally activated population of conduction bands can cause the semiconductor material to be somewhat transparent to certain wavelengths (eg, from 1000 nm) at room temperature and become opaque at high temperatures. Thus, as the temperature of the carrier plate increases, the absorbance and irradiance can increase rapidly. This effect depends inter alia on the structure of the semiconductor (amorphous / crystalline) and the doping. For example, pure silicon shows a significant increase in radiation from about 600 ° C. and reaches saturation from about 1000 ° C.

The spectral irradiance ε of the material of the carrier plate is at least 0.6 at a temperature of 600 ° C. for wavelengths of 2 μm to 8 μm. According to Kirchhoff's Law of Radiation, the spectral absorbance α _λ and the spectral irradiance ε _λ of an entity in thermal equilibrium are equal to each other:
α _λ = ε _λ (1)

Thus, the semiconductor component provides infrared radiation by the substrate material. Spectral irradiance ε _λ can be calculated as follows if the directional hemispherical spectral reflectivity R _gh and transmission T _gh are known:
ε _λ = 1−R _gh −T _gh (2)

  In this context, “spectral irradiance” is understood to be “spectral standard irradiance”. This is determined by the measurement principle known under the name of “Black-Body Boundary Conditions” (BBC), which is “Transmission and emissivity measurements of transparent and translucent materials at high temperatures. (DETERMINING THE TRANSMITTANCE AND EMITTANCE OF TRANSPARENT AND SEMITRANSPARENT MATERIALS AT ELEVATED TEMPERATURES) "; Manara, M .; Keller, D.C. Kraus, M .; Arduini-Schuster; 5th European Thermal-Sciences Conference, The Netherlands (2008).

Thus, the semiconductor material, particularly preferably the elemental silicon used, has the effect of making the vitreous matrix material black and making it black at room temperature, but also at high temperatures, for example above 600 ° C. As a result, good radiation characteristics for high bandwidth broadband radiation at high temperatures are achieved. The semiconductor material, preferably elemental silicon, forms a unique Si phase dispersed in the matrix. This phase may comprise a plurality of metalloids or metals (however, limited to a maximum of 50 wt.%, More preferably no more than 20 wt.%, Based on the weight fraction of the additional components). In this connection, the carrier plate material does not exhibit open porosity, exhibits a closed porosity of at most less than 0.5% and has a specific gravity of at least 2.19 g / cm ³ . It is therefore suitable for infrared emitters where the purity or hermeticity of the carrier plate is important.

  For use as a material emitting infrared radiation for an infrared emitter according to the invention, the carrier plate material is covered with a printed conductor, preferably provided as a baked thick film layer.

  Such thick film layers are made from a resistive paste by screen printing or from a metal-containing ink by ink jet printing and subsequently baked at high temperatures.

  With regard to the temperature distribution being as uniform as possible, it is advantageous if the printed conductor is provided as a line pattern covering the surface of the carrier plate so that an intervening space of at least 1 mm, preferably at least 2 mm, remains between adjacent sections of the printed conductor. Proved to be

  High absorption capability of the carrier plate material allows for uniform radiation even if the printed conductor occupancy density on the heated surface is relatively low. Low occupancy density is characterized in that the minimum distance between adjacent sections of the printed conductor is 1 mm or more, preferably 2 mm or more. A large distance between the printed conductor sections prevents flashover that can occur during operation with high voltage, especially under vacuum. The printed conductor extends, for example, in a spiral or serpentine line pattern.

  In order to reduce possible corrosion attacks on the material of the printed conductor, the carrier plate on which the printed conductor is applied can be placed in a cladding tube under vacuum or in a group of nitrogen, argon, xenon, krypton or deuterium. Preferably, it is maintained in a protective gas atmosphere containing one or more gases from.

  The infrared emitter according to the invention is particularly suitable for vacuum operation, but in each case a protective gas atmosphere surrounding the carrier plate in the quartz glass cladding is also sufficient to prevent oxidative changes to the printed conductor material.

  In an advantageous embodiment of the infrared emitter according to the invention, it is proposed that a plurality of individually electrically controllable printed conductors are applied on the carrier plate.

  Providing multiple printed conductors allows for individual control and adaptation of the irradiation intensity achievable with infrared emitters. On the one hand, the radiation output of the carrier plate can be adjusted by appropriate selection of the distance between adjacent sections of the printed conductor. In this connection, the sections of the carrier plate are heated with different intensities so that they emit infrared radiation with different irradiation intensities. By changing the operating voltage and / or operating current applied to each printed conductor, the temperature distribution within the carrier plate can also be adjusted easily and quickly.

  Furthermore, an advantageous embodiment of the invention is that a plurality of carrier plates with printed conductors are arranged in the cladding tube, whereby each carrier plate can be electrically controlled individually. This embodiment of the invention allows for emitter variations adapted to the geometry of the heated article. Thus, by arranging a plurality of carrier plates in a single cladding tube in a row, for example, panel radiators with different radiation intensities can be implemented in the individual partial areas based on the individual control of the carrier plates.

Furthermore, it has been found that it is advantageous if the cladding tube has a coating made of quartz glass that is opaque and highly reflective in partial areas. In particular, in order to form a slit-shaped emitter, it is advantageous that the coating is applied around the cladding tube in an angular range of 180 ° to 330 °. Such a coating reflects the infrared radiation of the heated filament, thereby improving the efficiency of the infrared radiation with respect to the heated article. The coating, also called the reflective layer, is made of opaque quartz glass and has an average layer thickness of about 1.1 mm. It is characterized by no cracks and a high density of about 2.15 g / cm ³ and is thermally stable at temperatures above 1100 ° C. The coating preferably covers an angular range of 330 ° around the cladding, so it does not occupy an elongated partial area corresponding to the strip shape of the cladding and is transparent to infrared radiation. This design facilitates the manufacture of so-called slit-shaped emitters.

Fig. 3 shows a schematic partial view of an infrared emitter incorporated in a cladding tube made of quartz glass. 1 shows a cross-sectional view of a cladding tube with an infrared emitter according to the invention. Fig. 2 shows a diagram of the radiation characteristics of an infrared emitter according to the invention compared to a conventional emitter with a Kanthal coil.

EXAMPLES In the following, the present invention will be described in more detail based on examples.

  FIG. 1 shows a first embodiment of an infrared emitter according to the invention incorporated in a cladding tube 101 made of quartz glass and generally assigned the reference numeral 100. The cladding tube 101 has a longitudinal axis L. FIG. 1 shows a partial view of an infrared emitter 100 having a carrier plate 102, a printed conductor 103, and two contact areas 104 a, 104 b for electrical contact of the printed conductor 103.

  The contact regions 104 a and 104 b have thin wires 105 a and 105 b welded to them, and these thin wires 105 a and 105 b lead to contact surfaces 106 a and 106 b in the crimping portion 107 in the connection socket 108 of the cladding tube 101. The thin wires 105a, 105b have 5 mm spring wire coils 115a, 115b longitudinal sections to compensate for wire thermal elongation at high operating temperatures.

  In the connection socket 108, the contact wires 109a and 109b are guided to the outside, and are similarly connected to the contact surfaces 106a and 106b in the crimping portion 107 by welding.

  A negative pressure (vacuum) is established inside the cladding tube 101 or an inert gas is used to create a non-oxidizing atmosphere inside the cladding tube, which causes the non-precious metal printed conductor 103 to be oxidized. Protected.

The carrier plate 102 includes a composite material having a matrix component in the form of quartz glass. In the matrix component, the elemental silicon phase is uniformly distributed in the form of a non-spherical region. The matrix looks transparent to translucent by visual inspection. When viewed under a microscope, it does not show open pores and at best shows closed pores with a maximum average dimension of less than 10 μm. The elemental silicon phase is uniformly distributed in the matrix in the form of non-spherical regions. It accounts for 5% weight fraction. The maximum average dimension (median value) of the silicon phase region is in the range of about 1 μm to 10 μm. This composite material is hermetic, has a density of 2.19 g / cm ³ and is stable up to a temperature of about 1150 ° C. in air. The embedded silicon phase, on the one hand, not only contributes to the overall opacity of the composite material, but also affects the optical and thermal properties of the composite material. This composite material exhibits high absorption of thermal radiation and high irradiance at high temperatures. The carrier plate 102 is black in appearance, has a length l of 100 mm, a width b of 15 mm, and a thickness of 2 mm.

  The irradiance measured for the composite material of the carrier plate 102 in the wavelength range of 2 μm to about 4 μm is temperature dependent. The higher the temperature, the higher the radiation. At 600 ° C., the standard irradiance in the wavelength range of 2 μm to 4 μm exceeds 0.6. At 1000 ° C., the standard irradiance over the entire wavelength range of 2 μm to 8 μm exceeds 0.75.

  The printed conductor 103 is formed in a meandering shape. The material of the printed conductor 103 also essentially comprises non-noble metals such as tungsten and molybdenum or polysilicon, whereby a correspondingly laid-out printed conductor is applied to the carrier plate 102 with a screen-printable paste and then baked. .

In another embodiment of the infrared emitter according to the invention, the carrier plate 102 comprises a ceramic material made of silicon nitride (Si ₃ N ₄ ) or silicon carbide (SiC), both of which are dark gray to black in appearance. . The carrier plate having the base material layer made of SiC is provided with a surface layer made of SiO ₂ that is electrically insulating with respect to the metal printed conductor.

  Glass ceramics with a dark brown or dark gray appearance (eg NEXTTREMA®) are also suitable as carrier plate materials, as are glassy carbon carrier plates such as plates made of SIGRADUR® material, for example. Yes.

  Another alternative material for the carrier plate 102 is a polyimide plastic material that can be heated to temperatures up to 400 ° C. Particularly for applications where a fast power-on time (of a few seconds) is required, a carrier plate made of a polyimide film having a low thermal mass is advantageous. Also in the case of this polyimide film as the carrier plate 102, a non-noble metal printed conductor 103 is applied. Since it is incorporated in a cladding tube made of quartz glass, it can operate in a non-oxidizing atmosphere.

  FIG. 2 shows a cross section perpendicular to the longitudinal axis L of the cladding tube 101 in which the infrared emitter is arranged. A reflector layer 200 made of quartz glass is applied to the outer peripheral surface of the cladding tube 101 over a length corresponding to the length of the carrier plate 102 to cover the surrounding 330 °. This gives a so-called slit-like emitter having an elongated open surface on the cladding tube, which passes infrared radiation emitted from the carrier plate to the outside.

  FIG. 3 shows the output spectrum of an infrared emitter according to the invention (curve A) compared to an infrared emitter equipped with a Kanthal coil (curve B). In this case, the carrier plate of the infrared emitter according to the invention is formed by a composite material comprising a matrix component in the form of quartz glass and an elemental silicon phase uniformly distributed therein, as described in more detail above. Is done. The printed conductor material in this case is tungsten. The temperature of the printed conductor of the carrier plate of the IR emitter is adjusted to 1000 ° C. A reference emitter with a Kanthal coil is also operated at a temperature of about 1000 ° C. It is clear that the infrared emitter according to the invention has an output about 25% higher than the reference emitter represented by curve B in the wavelength range of 1500 nm to about 5,000 nm at the peak of curve A.

  100 Infrared emitter, 101 cladding tube, 102 carrier plate, 103 printed conductor, 104a, 104b contact area, 105a, 105b fine wire, 106a, 106b contact surface, 107 crimping part, 108 connection socket, 109a, 109b contact wire, 115a, 115b Spring wire coil, 200 reflector layer

Claims (15)

  In an infrared emitter having a quartz glass cladding (101) surrounding a heating filament as an element emitting infrared radiation, the element being connected to an electrical connector outside the cladding via a current feedthrough The heating filament includes a carrier plate (102) having a surface made of an electrically insulating material, whereby the surface is covered with a printed conductor (103) made of a material that generates heat when a current flows. Infrared emitter characterized by   Infrared emitter according to claim 1, characterized in that the material of the printed conductor (103) is a non-noble metal. The material of the printed conductor (103) is tungsten (W), molybdenum (Mo), silicon carbide (SiC), molybdenum disilicide (MoSi ₂ ), chromium silicide (Cr ₃ Si), aluminum (Al), tantalum Infrared emitter according to claim 1 or 2, characterized in that it comprises one or more components from the group of (Ta), polysilicon (Si), copper (Cu) and heat resistant steel.   Infrared emitter according to any one of claims 1 to 3, characterized in that the carrier plate (102) is made of at least two layers of material.   Infrared emitter according to any one of the preceding claims, characterized in that the carrier plate (102) comprises a composite material formed by a matrix component and an additional component in the form of a semiconductor material. Infrared emitter according to claim 5, characterized in that the matrix component is quartz glass, preferably having a chemical purity of SiO ₂ of at least 99.99% and a cristobalite content of at most 1%.   6. Infrared emitter according to claim 5, characterized in that the additional component comprises a semiconductor material in elemental form, preferably elemental silicon.   The additional component is present in the carrier plate (102) at a temperature and temperature of 600 ° C. in a type and amount that provides a spectral irradiance ε of at least 0.6 for a wavelength of 2-8 μm. The infrared emitter according to claim 5. The carrier plate (102) according to any one of the preceding claims, characterized in that the carrier plate (102) exhibits a closed porosity of less than 0.5% and has a specific gravity of at least 2.19 g / cm ³ . Infrared emitter.   Infrared emitter according to any one of the preceding claims, characterized in that a plurality of individually electrically controllable printed conductors (103) are applied on the carrier plate (102). .   A plurality of carrier plates (102) with printed conductors (103) are arranged in a cladding tube (101), whereby each of the carrier plates (102) can be electrically controlled individually. The infrared emitter according to any one of claims 1 to 10.   The carrier plate (102) on which the printed conductor (103) is applied is one in the cladding tube (101) under vacuum or from the group of nitrogen, argon, xenon, krypton or deuterium. The infrared emitter according to any one of claims 1 to 11, wherein the infrared emitter is held in a protective gas atmosphere containing the above gas.   Infrared emitter according to any one of the preceding claims, characterized in that the printed conductor (103) is provided as a baked thick film layer.   Infrared emitter according to any one of the preceding claims, characterized in that the cladding (101) has a coating (200) made of quartz glass which is opaque and highly reflective in partial areas.   The infrared emitter according to claim 14, characterized in that the coating (200) is applied around the cladding (101) in an angular range of 180 ° to 330 °.

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